Tiny correction: The publisher was "(de) Marsan".

There are three copies of this song at the Bodley Ballads site. Two are undated, the third is from ca. 1850. They tend to vary most in the patterns used for the chorus (which bits are repeated and when). One gives the air as "A life on the deep", possibly meaning "A life on the ocean wave, a home on the rolling deep" (music by Henry Russell, 1838), a huge hit in its day. But given the variety of chorus patterns, I suspect it was sung to other tunes as well.

This song may have been discussed in other threads, but as the search engine is temporarily down for me, I can't verify this. In searching for information on "Le Ross", here's the best guesses I came up with:

The Mary Rose, a 16th century warship built by Henry VIII.

Philip Ras, a Dutch privateer and captain of the ship Heat, active in the 1650s in the "First English War".

George Ross, who, along with George Dunkin, William Eddy and Neal Patterson, was found guilty of piracy and hanged at Charleston, South Carolina, in 1718.

Murad Rais (Peter Lisle/Lyle), a Scottish pirate and Barbary corsair, captain of the Betsy, renamed Meshuda, active from 1796 to 1832. Given such a successful and long-lasting career, he would have been fresh within memory when this song was composed, though it would be hard to mistake this wild Barbarian for a Frenchman!